This happens a few times now. What happen is, after using Paladin's active skill that reflects enemy damage and if that kills the enemy, the game just bug out and you can no longer move but you can still click around and toggle the menu. Switching to auto mode doesnt make the AI move at all though. When this happens in arena, its registered as a loss to my team, because I have to reset the game and a disconnect in Arena is registered as a loss.